This book constitutes the refereed proceedings of the 8th International Conference on Software Reuse, ICSR-8, held in Madrid, Spain in July 2004. The 28 revised full papers presented were carefully reviewed and selected from numerous submissions. The papers are organized in topical sections on software variability: requirements; testing reusable software; feature modeling; aspect-oriented software development; component and service development; code level reuse; libraries, classification, and retrieval; model-based approaches; transformation and generation; and requirements.